On Tue, 25 Sep 2018 19:16:15 -0400 Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote: > Abstract: > ======== > > On s390, we have cryptographic coprocessor cards, which are modeled on > Linux as devices on the AP bus. Each card can be partitioned into domains > which can be thought of as a set of hardware registers for processing > crypto commands. Crypto commands are sent to a specific domain within a > card is via a queue which is identified as a (card,domain) tuple. We model > this something like the following (assuming we have access to cards 3 and > 4 and domains 1 and 2): > > AP -> card3 -> queue (3,1) > -> queue (3,2) > -> card4 -> queue (4,1) > -> queue (4,2) > > If we want to virtualize this, we can use a feature provided by the > hardware. We basically attach a satellite control block to our main > hardware virtualization control block and the hardware takes care of > most of the rest. > > For this control block, we don't specify explicit tuples, but a list of > cards and a list of domains. The guest will get access to the cross > product. > > Because of this, we need to take care that the lists provided to > different guests don't overlap; i.e., we need to enforce sane > configurations. Otherwise, one guest may get access to things like > secret keys for another guest. > > The idea of this patch set is to introduce a new device, the matrix > device. This matrix device hangs off a different root and acts as the > parent node for mdev devices. > > If you now want to give the tuples (4,1) and (4,2), you need to do the > following: > > - Make sure the queues (4,1) and (4,2) belong to vfio_ap (see patches > #5 and #6) > - Create the mediated device. > - Assign card 4 and domains 1 and 2 to the mediated device > - Optionally activate the mediated device. > > QEMU will now simply consume the mediated device and things should work. > > For a complete description of the architecture and concepts underlying > the design, see the Documentation/s390/vfio-ap.txt file included with this > patch set. > > v10 => v11 Change log: > ===================== > * Fixed race condition when setting KVM in the notifier > * Removed KVM_S390_VM_CPU_FEAT_AP, no longer necessary > * Fail vfio_ap module inti if AP instructions not available on host > * Remove KVM_S390_VM_CPU_FEAT_AP > * Expose VM enable/disable APIE attributes only if AP instructions > available on host. I think this version is good to go with the touchups mentioned.
